Why is the universe comprehensible? by Ian Durham

Dear Ian,

"Why is the Universe so comprehensible?" A great topic to which you have written a most stimulating essay.

I think our world is comprehensible because humans are good at searching out and then explaining patterns. First in natural science, then in our own creation - mathematics. As our science progressed, some of the patterns, or our deductions about them became established as our principles or laws - especially where symmetry was involved.

I believe, like Einstein, that `comprehensibility' means a scientific understanding of the universe's functional composition. In my essay I cover how the 3 Un's have impinged on my thinking as I work towards my goal of 'Structural Physics'.

If a condition of comprehensibility is one of measurement, and as you quoted "Feynman once famously said, if something disagrees with experiment then it's wrong", then isn't defining the experiment and its measurement in a truth-conditional way extremely important. Some might argue that is where EPR experiments have come unstuck. Part of the price of comprehensibility is the way we design our experiments.

On another thought-line, you stated: "Markus Muller recently constructed a self-consistent theory in which an objective external world emerges from more fundamental observer states." Isn't this similar in some way to applying Susskind and 't Hooft's idea of a holographic black hole event horizon to the Universe through multiple observer states? After all, Muller thinks the link between entropy and information remains, possibly leading to a holographic principle.

Thanks for your essay as it has extended the boundaries of my thinking.

Lockie Cresswell

Dear Ian,

I am absolutely delighted by this essay. One of the things you touch on is the separability (for lack of a better word) of the universe. We can make sense of it because of how explanations remain "in their proper bounds".

One thing I'm curious about: are there examples in "normal" life where explanations go out of bounds? i.e., you write "While it is impossible to prove that the answer to the question "what color is my hair?" will never be "narrow" or "dog", the fact remains that it is highly unlikely." It is possible to come up with an example that (however unlikely) violates the Principle of Comprehensibility?

Yours,

Simon

(You can find some remarks on "mutual explainability" in my contribution this year, for which I'd love to have your thoughts--please feel free to drop me a line by e-mail or as you please, because I think there's a lot of philosophical literature for me to learn from.) https://fqxi.org/community/forum/topic/3492

Dear Professor Ian Durham,

Thanks!

And, I am glad you found my remarks worthwhile.

Best,

Raiyan Reza

Hi Ian,

I waited a while to read your essay as I thought, comprehensibility is a too incomprehensible expression in order to get something comprehensible out of it. I was wrong. It was a clear enjoyable read. A few questions however remained that I would like to ask and a few remarks I would like to make.

It seems to me, that you the context, under which a question can be comprehensive, must be classical. I completely agree, that the very meaning of a spin, implies the possibility to make an experiment along some direction and that we can know in which direction has been made (and share this information). This means that the directions must be somehow classically distinguishable. They can be constructed as coherent spin states. But could you imagine, that someone holds a superposition of two such 'classical' states as context and not being able to agree with you in which direction the spin measurement has been done? Or do you see limits in the applicability of the superposition principle?

I personally cannot really get some operation meaning from such a superposition, as normally the superposition is not an eigenstate of a generator of the group SU(2) representation except for the lowest non trivial representation 1/2. But then one of the main principles of the QM seem to have only limited applicability.

In a similar matter you seem to look for a reconciliation between the subjective view and an objective one. This seem to me is a problem brought to us mainly in QM and specifically by Wigner's friend type experiments. Does the stability of the universe also here play a role for the comprehensibility of the experiment?

The stability of the universe sounds for me extremely dramatic and I do not know what you exactly count as stable. I asked this last question, because in my essay, the condition for an experiment to be comprehensible (I call it definable or measurable in my essay), is to be unitary and symmetric. So if Wigner tries to measure his friend being in the superposition with the probe, he breaks unitarity and symmetry within the friends subsystem. So Wigner trying to make a incompatible measurement on his friend would be enough to destroy the stability of his friends lab experiment.

You actually do not answer the question of why the universe is comprehensible, but of under which conditions it is. I would be happy, if you would find the time to read and comment on my essay that has a similar topic. I ask under which physical condition physical concepts are definable.

Luca

Dear Ian,

Good essay, interesting view. I agree there "..exist problems that are undecidable for physical reasons" and "The universe has fundamental limits baked into it." but can we not reduce them to 'infinitessimals'? If you interact with a spinning sphere at the equator and I ask; 'Is it + or - rotation?' Can you tell me? But how CLOSE to the equator must we be get 50:50 certainty? Is that not, as I think you suggest, just a matter of experimental precision, so can be reduced!? Now that +/- decidability also INCREASES, by CosTheta Latitude, from 0 to 1 towards the poles.

So now consider your Stern-G Fig.1.; We know all light has ellipticity, as do all orbitals, so if we hypothesise polariser interactions can change ellipticity (major axis orientation) as well as polarity, then we can say the magnets divert the 'state' BOTH WAYS, but only ONE channel corresponds to major axis amplitude so can 'click'.

Now in THAT case, with some simple conditions (shared axis, and vector additions) we can surely reduce 'quantum uncertainty' to the physical limit you suggest!? I've found that a powerfully resolving hypothesis, as I discuss in my own essay, giving Bells inequalities physically, as he always suggested was possible.

We can then ask the truth value question; "is my hair blond?" and get answers of recursively reducing precision of HOW blonde!? So a 'reducing' not 'excluded' middle between Blonde and Brunette.

You struggled with that concept last year, perhaps even ran from it as some do. Now I think it should be more comprehensible from your own viewpoint. Do let me know.

Very best

Peter

Dear Ian,

which color of hair would a pre-colonial Bantu have assigned to Marilyn Monroe? And what about an alien from a planet orbiting Sirius ?

"The universe has fundamental limits baked into it." Isn't it rather so that these 'limits' are constitutive means for there being something at all - FOR US?

Heinz

Hello Ian, Neil Bates here. I am very impressed by the literary quality of your piece, as well as the broad interdisciplinary scope and variety of picking various conceptual metaphors and points to make. Certainly something worthy of publication in a semi-popular science education forum. I must agree that issues of language in science and even basic description of experience can't be brushed aside. Too often, authors take the material of their discussions as simple clear givens. This is so despite decades of wrangling over the philosophical problems of quantum mechanics and even the scientific method. It is important in issues of the peculiar "Renninger null measurement" where we presume a "wavefunction" must have rearranged because a detector that COULD have found a particle showed a negative result. And what about unreliable detectors? Can they have ontological significance?

I haven't seen much similar to your speculations about the effective relativity of calculation. Some would say "so what" because math is conceived as a perfect Platonic thing in itself, yet foundational mathematicians still argue over discovery versus construction, the viability of unmet counterfactuals, etc.

Also: If you or other readers might take at look at my own piece, addressing the issue of the strong correlations of entanglement and how neo-mechanistic models of quantum physics aren't enough - it could use some votes on this last day. Thank you.

Ian,

OK, the hypothesised mechanism seems still beyond your analytical skills. Or did having to decide or - rotation exactly at an equator confuse you? No surprise as you're in the vast majority, just a little disappointing a possible answer before our eyes still seems invisible to most!.

Best

Peter

YW. BTW folks, sorry if I offended anyone by mentioning the "v" word. The deadline sneaked up on me (can I say "snuck"?) and I worried about it (and is it really EST, or EDT?) Yeah, just commenting or mentioning one's own essay is an implicit invitation to that very thing, but appearances are what they are - as we might haggle over in physics.

"As long as the universe remains relatively stable, the first condition implies the second. The fact that the universe remains relatively stable, thus ensuring that the second condition is met in the aggregate, was originally proposed as a "principle" of comprehensibility in [7]. It asserted that the nature of a physical system under investigation will always remain within the bounds of the method of investigation. That is, we expect scientific answers to scientific questions. Of course, one could object to the use of the word 'always' as there is no way to prove this. In fact it is really a statement of tendencies within physical systems akin to the Second Law of Thermodynamics. Is it better to say that the entropy of the universe only tends to increase rather than stating that it always increases? I would rather hedge my bets and assume the weaker condition even if it has never been observed to decrease. Likewise with the principle of comprehensibility. In terms of truth-conditional statements, then, we can restate this principle of comprehensibility as follows."

By simply asking a question, we immediately establish a context which limits the scope of the inquiry. The general stability of the universe ensures that answers to our question will, to a high degree of probability, remain within the context of the question. This is the essence of comprehensibility since it allows us to develop systematic measures by which we can further probe a topic. Building an understanding requires refining the context by asking additional questions. But this also necessarily means that our knowledge is shaped by the questions we ask and how we choose to ask them, i.e. by our methodology

"In Newton's day, testing the truth-conditional statement "time is absolute" would have produced a positive truth value given the knowledge and technology of the time. That same statement, if tested now, would elicit a negative truth value. Yet it is wrong to say that there was any change in the underlying physics between then and now. What changed was our knowledge of that physics, i.e. we increased our information. Yet even if we take Braun's view it is clear that limitations still exist and that these limitations intimately depend on context. Our inability to simultaneously measure non-commuting observables in quantum systems to arbitrary accuracy is a limit on our ability to obtain information regardless of whether or not we believe in objective truth. It arises from the context of our measurement. Comprehensibility is still the result of a combination of the mutual agreement between observers and the fact that the universe remains relatively stable. That is to say, the Principle of Comprehensibility need not be formulated in a truth-conditional form. The fact remains that in order to say we comprehend some element of the universe we must necessarily obtain some information about that element. But obtaining that information is a physical process that necessarily has a context which constrains the nature of that information; the very act of acquiring information shapes the information acquired. Physical limitations on the acquisition of knowledge are not controversial. The universe has fundamental limits baked into it. But it is these very limits that allow for the universe to be comprehensible. They are necessary in order for our seemingly finite minds to have any hope of comprehending anything. These physical limitations bear a certain resemblance to G¨odel's incompleteness theorems in that they arise from the internal structure of the system and one must break free from that structure in order to fully understand it. The universe is a vast and interconnected place of which we are but a small part, a mere mote of dust, as it were. Any attempt to comprehend it must necessarily depend on the fact that we are a part of it. Indeed the very act of comprehension is itself a part of it and is thus shaped by it. Like the god Odin from Norse mythology, who is said to have sacrificed an eye in order to attain wisdom, our quest for comprehension limits our very ability to comprehend, and the universe remains always partially veiled."

JP: I will rate your essay just before the time for rating expires. It is a privilege to be able to read what you write and to offer comments.

Hi Ian,

I found the theory of quantum reference frames is very interesting (as you might imagine after having read my essay). I heard in a talk you gave at a FQXI conference, that you are working on quantum reference frame. But sadly, I could not find any paper you published on the topic.

Thanks also for the interest and reply on my essay. I tried to gave an answer to the point you raised about the existence of semantically closed theories, if you are interested.

Luca

Hi Ian,

please have a look at my reply in my blog regarding closeability of SR.

Luca

Hi Ian,

Thank you, any feedback would be helpful. Hope your essay does well in the judging.

Jeff